A surface light-source device is used as a backlight unit of a liquid-crystal display, an indication light for advertisement and sign, and so forth. For instance, in Japanese Patent Laid-Open Publication No. 2005-234397, a rod-like light source of a fluorescent lamp or the like is used and light emitted from the circumference of the rod-like light source is guided by a light guide plate so as to uniformly emit the light from a light emission surface of the light guide plate.
When the fluorescent lamp is used such as described in the above-noted Publication, the surface light-source device has a limitation to reduction of thickness due to a diameter of the fluorescent lamp. In this regard, it is considered that a light-emitting element of an LED and so forth is disposed instead of the fluorescent lamp. However, although the light from the LED generally has emission distribution resembling cos θ to the Nth power, an emission amount is large in an upward direction. Consequently, an amount of the light emitted from the light emission surface of the light guide plate becomes large at an overhead portion of the LED. Thus, there arises a problem in that emission unevenness of the light emission surface of the light guide plate is conspicuous in comparison with the case using the fluorescent lamp.